Construction of a Triazine-Based Fluorescent MOF for Aqueous Cr2O72– Detection and Gas Adsorption

Previously, we reported a 1,3,5-triazine-based metal–organic framework (MOF) constructed via the in situ hydrolysis of melamine. However, the use of template molecules within the pores posed significant challenges for material activation and resulted in pronounced fluorescence quenching. In this work, we introduce a more sustainable and template-free synthetic strategy by directly employing ammeline as the organic ligand to construct a triazine-based MOF, SXU-120(ammeline). This approach simplifies the activation process, enhances solid-state fluorescence, and improves stability. The resulting MOF demonstrates high sensitivity and selectivity for aqueous Cr2O72– ions, achieving a Stern–Volmer quenching constant (KSV) of 5.13 × 104 M–1. Furthermore, a scalable reflux-based synthesis route was developed, reinforcing the material’s potential for practical and eco-friendly environmental sensing applications.